Chemistry (12th Edition)

by
Wilbraham

Published by
Prentice Hall

ISBN 10:
0132525763

ISBN 13:
978-0-13252-576-3

Chapter 17 - Thermochemistry - 17 Assessment - Page 587: 71

Answer

a. The enthalpy change type is Vaporization. This is an endothermic reaction.
b. The enthalpy change type is Solidification. The reaction is an exothermic reaction.
c. The enthalpy change type is Condensation. The reaction is exothermic.
d. The enthalpy change type is Solution. Since it is absorbing heat, the reaction is endothermic.
e. The enthalpy change type is Fusion. The reaction is an endothermic reaction.

Work Step by Step

It is vaporization because it is liquid to gas. Also, the reaction is endothermic because the liquid is absorbing heat to become a gas. Just think of boiling water on a stove. All of the steam you see coming out of the pot is all vaporization.
It is solidification because it is turning from a liquid to a solid. The reaction is exothermic because to turn from a liquid to a solid, it must lose heat. Just think of freezing water in the freezer. The more heat that is taken away, the colder it gets, eventually causing it to freeze and maybe make some snow cones or popsicles.
Heat of solution is a tricky concept. There is no opposite reaction of heat of solution except for the loss of heat of solution. I don't know why they didn't just call the loss of heat of solution the heat of dissolution, but that's just how it is. Just think of it this way, if it is adding heat, it's endothermic, if its losing heat, its exothermic. Just think of tea and how the more heat you add, the more the oils in the leaves dissipate to mix with the water forming a delicious solution.
It is condensation because it is turning from a gas into a liquid. The reaction is exothermic because the gas must lose heat to become a liquid. Think of rain and how clouds are vapor puffs and when there is too much vapor, the vapor starts to condensate forming precipitation. That's not exactly how it happens, but the point is, just think of clouds forming rain.
It is fusion because it is turning from a solid into a liquid. The reaction is endothermic because a solid must absorb heat to turn into a liquid. Just think of if you whip and fuse a rope. You are melting the rope by heating it up, thus turning the fibers into a liquid.